Nonskid crepe rubber composition



Patented June 23, 1953 NONSKID CREPE RUBBER COMPOSITION Cecil F. Backus,Wilmington, Del.

No Drawing. Application April 2, 1949, Serial No. 85,257

2 Claims.

This invention pertains to a moldable, selfadherent, non-skid crepecoating composition and to a method for preparing the same. Forillustrative purposes only the invention will be particularly describedas utilized in connection with the heeling and soling of shoes, althoughit is obviously not limited thereto.

Crepe shoe soles now available generally owe their name to their grainy,crinkled appearance and are usually applied as a thick sole to sportshoes. These crepe soles, however, are soft and often sticky and theirwearing qualities are sacrificed for rugged appearance. Furthermore,such soles readily slip on painted, varnished or waxed wood, linoleum ormarble floors, or polished brick or concrete floors when wet with water,grease, gasoline, etc.

Compositions used to make crepe soles usually contain rubber, rubbertype polymers, or mixtures of these which are vulcanized, cured andsheeted at the plant. The resulting crepe type material, in sheet orboard form, is cut to size by the skilled shoe worker or repairman whenmaking or repairing shoes. These crepe soles can also be stamped orpressed in different shoe sole and heel sizes at the plant thusrelieving the worker of some wasteand the extended cutting step requiredto shape the crepe shoe sole material.

Before the crepe sole is placed on the shoe bottom, an adhesive or abinder is applied to the shoe bottom or sole to secure the two togetherand this step may require the application of heat and pressure to insurea good bond. Furthermore, where vulcanization or gluing is not suitable,it is customary to rivet, nail, sew, or by similar mechanical meanssecure the sole to the shoe bottom.

Thus, it is apparent that prior processes of producing crepe solematerial have resulted in crepe materials which readily slip on wetsurfaces or pavements and which have required the steps of vulcanizing,sheeting, cutting, or stamping, etc., the crepe sole material before itis placed on the shoe bottom necessitating skilled workmanship, with thefurther requirement of an additional material, and very possibly anadditional step being needed to secure the crepe sole to the shoe bottomwhen soling or resoling shoes. 7

It is, therefore, an object of this invention to provide a moldable,non-skid, self-adherent crepe coating composition.

It is another object of this invention to provide a non-skid, crepe shoesole composition that 2 can be shaped without cutting or stamping andcan be secured to shoe bottoms without the need of adhesives, heat,pressure, or mechanical attaching means.

It is still another object of this invention to provide a method formaking a non-skid, crepe shoe sole composition characterized by the factthat it can be directly applied to shoe bottoms and .shaped withoutcutting or stamping and without the necessity of employing adhesives,heat, pressure, or mechanical securing means.

It is yet another object of this invention to provide shoes withnon-skid, self-adherent, crepe rubber heels and soles.

It is a further object of this invention to provide a method forapplying a non-skid, crepe shoe sole composition to a shoe bottomwithout the necessity .of cutting or stamping the material or ofapplying heat, pressure, adhesives, or mechanical securing means.

It has now been found that a moldable, nonskid, self-adherent,crepe'shoe sole composition can be obtained by dispersing finely'dividedrubber and fibers in a neoprene solution. On applying the composition toa shoe bottom before the grated rubber has dissolved in the solution andwith evaporation of the solvent, a nonskid, crepe sole results that isself-adherent and tough.

In general, when practicingthe invention disclosed herein, it is firstnecessary 'to prepare a neoprene solution in which theground rubber canbe dispersed. This solution is conveniently prepared by first millingpolymerized chloro-2- butadiene-lB of the AC type until it breaks downand will readily dissolve in a volatile hydrocarbon solvent. After thechlorobutadiene has dissolved in the solvent, a filler, part of which isfibrous, and a tackifier are added to the solution to form a basecomposition. The rubber is then, .grated'and mixed with this basecomposition until a thorough mixture has been obtained. Before therubber has dissolved in the base composition, the mixture is applied bymeans of a spatula to a roughened, dry, cleaned shoe bottom. Onevaporation of the solvent from the mixture, 2. grainy and corrugatedselfadherent, non-skid crepe shoe sole is obtained.

The polymerized chloro 2 butadiene 1,3 of the AC type as manufactured bythe Du Pont Company, hereinafter called neoprene, should conform to ASTMrequirements shown in their specification entitled Tentative method oftest for plasticity and recovery of rubber and rubberlike materials bythe parallel plate plastometer,"

ASTM-D-926-47-T, with plasticity numbers (readings made in mm.) of 302to 377 and recovery numbers of 38 to 53 at 80 C. and three minutes. Theneoprene has a specific gravity of about 1.23, and it can contain tracesof iron compounds, some soap or antioxidants such as are well known tothose skilled in the art.

If about 1 pounds of this neoprene are milled on a two-roll,water-cooled 12-inch rubber mill for less than about minutes, however,or not at all, the neoprene swells in the hydrocarbon solvent and willnot readily go into solution to form a base composition that can be usedas an adhesive carrier for the ground rubber to make crepe soles and asan adhesive to secure the composition to the shoe bottom. On the otherhand, if the neoprene ismilled for over 30 minutes, it has been foundthat the resulting base composition has become too soft and sticky, anddue to too much cold flow it lacks the quality of retaining its shapewhen applied to shoe bottoms after addition of the ground rubber and onevaporation of the solvent. A milling period of from about 10 to about30 minutes has been found to give very satisfactory results. The crepeshoe sole composition made with this milled neoprene after being appliedto the shoe bottom and on evaporation of the solvent does not exhibitany tendency to cold flow. Excellent crepe shoe sole compositions havebeen obtained when using neoprene milled for about twenty minutes. Theplasticity numbers of the milled neoprene should be from about 280 to355 at 80 C. Although it has been shown above that the plasticitynumbers for the neoprene before milling are from about 302 to 3'77, thisunmilled neoprene lacks desirable adhesive properties (although it willdissolve somewhat in about 50 per cent of the aromatic solvent), itsmolecular structure is such that it will swell or gel in the solvent, orwill not properly go into solution until it has been milled for fromabout 10 to about 30 minutes. Milling this neoprene, thus, appears tochange its molecular structure and prevents any tendency to form gelsresulting in a polymer that will readily dissolve in the solvent to forma base composition having excellent adhesive properties.

Milling also changes the viscosity of the neoprene solution. Forexample, a solution of an unmilled neoprene having a plasticity numberof 330 will have a viscosity of from 1 to 1 minutes while a solution ofmilled neoprene of the same plasticity will have a viscosity of to A;minute as shown by the modified Gardner- Holdt test. Since the neoprenehas been reduced in molecular size, or changed in molecular structure,it readily penetrates the fibrous leather surface of the shoe bottompermitting great adherence of the neoprene with the shoe bottom. It is,furthermore, not necessary to use milled neoprene of one plasticitynumber. 'For example, one-half of the milled neoprene used in thesolution can have a plasticity number of about 330 and the other halfcan have a plasticity number of about 280.

Other rubber milling machines can be used to mill the neoprene besidesthat disclosed above if the rollers are very closely positioned togetherand operated at different speeds so that the rubber is crushed andrubbed rather than rolled around. It is, of course, obvious to thoseskilled in the art that when milling on other machines, the time willvary somewhat from the above depending on the size of the rubber mill,the

quantity of neoprene, the speed of the rolls, the temperature, thespacing between the rolls, etc. For example, it will take from 40minutes to minutes to obtain sufficient milling on a 60 inch mill toresult in a milled neoprene having the above desirable properties asrepresented by its plasticity numbers of from 280 to 355. From 20 to 30minutes is required on a 30-inch mill. A refiner, i. e., a mill whereone roll is usually larger than the other and which is generally used inthe rubber reclaiming industry, can likewise be employed to mill theneoprene.

After milling, the neoprene is dissolved in a suitable hydrocarbonsolvent. This can be conveniently accomplished by adding the solvent tothe milled neoprene in a cement churn, or dough or paddle-type mixer.The milled neoprene can be grated, chopped, ground or otherwise finelydivided in order to facilitate dissolving it in the solution. This canbe obtained by first chilling or freezing the neoprene followed byfrictional disintegration, etc. The time required to mix and dissolvethe neoprene will vary from about two to about five hours depending onthe quantities of neoprene and solvent used. About three hours mixingtime at room temperature is usually sufficient to dissolve the milledneoprene.

It has been found that about parts by weight of milled neoprene can bedissolved in from about 250 to about 500 parts by weight of ahydrocarbon solvent. It is preferred to use from 100 parts by weight ofthe dry, milled neoprene to from 300 to 400 parts by weight of thehydrocarbon solvent. A solvent solution which provides excellent resultsis prepared by mixing from 40 to 60 parts by volume of toluene with from60 to 40 parts .by volume of gasoline. The primary function of thetoluene is to dissolve the milled neoprene while the primary function ofthe gasoline is to promote evaporation. Benzene or Xylene may besubstituted for toluene, and in place of the gasoline, .heptane, hexane,or pentane can be used. It is, of course, obvious to those skilled inthe art that many other hydrocarbon solvents can be utilized in thiscomposition besides those listed above.

While ground rubber can now be added to this composition to provide acrepe shoe sole composition that is applied to shoes without thenecessity of vulcanizing, heating, using pressure, adhesives ormechanical securing means and which, of itself, 'is strongly adherent tothe shoe bottom, certain specific resinous materials may be added to thebase composition, if found desirable, to improve somewhat the initialtack and bond strength of the resulting crepe sole composition. Thesematerials include wood rosin, wood rosin derivatives (such ashydrogenated methyl abietate), rosin ester derivatives such asStaybelite ester (polyhydric alcohol ester of hydrogenated rosin) orester gum (glycerol ester of rosin), phenol-formaldehyde resins,resorcinol formaldehyde resins, coumarone indene resins, etc. They aregenerally added to the neoprene base composition or solution prior tothe addition of the filler in the proportion of from about 2 to about 20parts by weight of the resin to about 100 parts by weight of the dry,milled neoprene although it has been found best to use from 5 to 10parts of resin to 100 parts of neoprene.

When the milled neoprene has completely dissolved in the solvent, andafter the resinous materials have been added thereto, a filler, of whichat least about 40 per cent by Weight is fibrous, is then added and mixedin with the solution. The fibrous filler is essential in producing anonskid type of crepe shoe sole. Although the outer surface of the crepesole, on first being formed, is rough and thus has some non-skidproperties, the fibrous filler materially increases the tack of the soleon slippery or wet surfaces. The nonskid property of the sole which isattributable to the fibrous filler is of great importance after thesurface of the sole has worn smooth, because the fibrous fillerpreventsthe sole from slipping or skidding. As each layer of material isworn away through use, a new surface layer is presented containing morefibrous material, which was dispersed throughout the sole materialduring preparation of the composition, so that the non-skid propertiesare maintained during the life of the sole. A strong milledneoprene-tofiber bond has formed after evaporation of the solvent givingexceptionally good tensile strength to the sole as well as flexibility.Since the neoprene solution or base composition contains a dispersion offibers therein and since the outer layers of the grated rubber particlesare in a gel or soft state, it is believed the fibers also extend fromthe matrix of milled neoprene into the outer layers of the rubberparticles, giving further strength to the mass on drying. The fibrousfiller also aids in promoting evaporation of the solvent. Thenon-fibrous filler aids in strengthening the sole, filling pores,shaping the sole, and improving the wearability of the resulting sole.Instead of adding the filler to the neoprene solution, it can be addedto the neoprene while it is being milled on the rubber mill, and, thus,the time of preparation of the shoe sole composition can be easilyreduced.

The total amount of filler, fibrous and nonfibrous, added to thecomposition is from about 20 to about 125 parts of filler per 100 partsof dry milled neoprene. It is desirable to use from 40 to 80 parts offiller per 100 parts of the neoprene. If more than about 125 parts offiller are used, the resulting crepe-sole composition is too viscous toapply readily by hand and adherence is poor while if less than about 20parts of filler are present, the composition is slow in drying, has poorwearability, and has lost its non-skid properties.

Examples of suitable fibrous fillers are cotton, or leather fibers,cellulose fiock, wood fiber, and synthetic yarn fibers (nylon, viscoserayon or cellulose acetate). These fibers can be used singly or mixed inany proportions. It is preferred to use a mixture of leather fibers andcotton fibers where the cotton fibers have lengths of from 0.060 inch to0.25 inch. From to 75 parts by weight of the fibrous filler per 100parts by weight of the dry milled neoprene are used in the compositionalthough it has been found best to use from to 50 parts of fiber per 100parts of the neoprene. If the fibers are micropulverized, their quantitycan be increased up to about 120 parts by weight.

Other organic and mineral fillers, having good abrasive and wearqualities can also be added in amounts up to about 60 per cent by weightof the total filler material in the neoprene solution. These additionalfillers can be added singly or mixed together and include rock wool,clay, hydrated calcium silicate, carbon black, metallic particles, woodflour, ground cork, nutshell meal or fiour, leather dust, leather blocksor particles, hard rubber dust, Vinylite or styrene and '6 othersynthetic or resinous dusts. These organic and mineral fillers can beadded to the composition in the ratio of from 10 to 50 parts of fillerper parts of the dry milled neoprene although it is preferred to addfrom 20 to 30 parts per 100 parts of the neoprene.

At the time the filler is added to the neoprene base composition orsolution in the mixer, a small amount of a dispersing agent can also beadded thereto to reduce the overall mixing time. From about /2 to about5 parts by weight of lignin per 100 parts .by weight of the dry neopreneis an excellent material for this purpose.

The milled neoprene in the base composition can liberate smal1 amountsof hydrochloric acid during storage or while in service with somedeterioration of cellulosic and other materials. It is, therefore,desirable in some cases to add acid acceptors to the composition. Forthis purpose about four parts of calcined magnesia and about five partsof zinc oxide per 100 parts of the dry neoprene can be used.

Small amounts of organic and inorganic dyes such as are well known tothose skilled in the art can likewise be added to the composition tochange its color if desired.

The grated, ground, or finely divided rubber can be readily prepared byfreezing and subsequent frictional disintegration as well known to thoseskilled in the art. A rubber mill or grinding machine can likewise beemployed for vulcanized rubbers. The rubber should be of sufficientfineness to pass through an 8 mesh size screen. Sizes substantiallylarger than this do not result in a strong crepe sole. The term rubberfor the purposes of this invention, is to be construed to meanvulcanized or unvulcanized natural rubber, S neoprene, "GRS (agovernment synthetic rubber-type S (for styrene) polymer produced frombutadiene and styrene, a polybutadienestyrene copolymer) or GN agovernment produced tough elastic product obtained by heating a plasticbenzene soluble polymerizable chloro- Z-butadiene-l, 3 polymer neoprene,AC neoprene, scrap rubber, e. g., red rubber tubes, natural rubbertubes, or butyl tubes; other synthetic rubbers like nitrile rubbers arealso appli cable. The rubber does not have to be milled as it is usedfor its wearing qualities and crepe effect and any adhesive propertiesthat it may have are only adventitious. It has, of course, certainnon-skid properties since it renders the surface of the sole rough andcorrugated. In the case of the grated unvulcanized S, AC, GRS or GN, ornatural rubbers, it is necessary to apply the shoe sole compositionwithin a short time after being mixed with the base composition as theseparticular rubbers tend not only to gel but to dissolve in the solventof the composition. Thus, on evaporation of the solvent the rough, crepeeffect is lost. However, if the shoe sole composition is used shortlyafter mixing, only a slight softening or gelling oi the outer layers ofthese rubber particles occurs permitting the grated particles tosubstantially retain their shape and to allow a bond to form betweenthese rubber particles and the continuous phase of the milled neopreneon evaporation or" the solvent thereby resulting in a strong crepe,non-skid sole. On the other hand, grated, vulcanized or cured rubbers donot apparently dissolve in the solvent over extended periods of timealthough they may tend to gel somewhat on their surfaces. Thus, the shoesole composition containing vulcanized 7 or cured S, AC, GRS or GN, andnatural rubbers, can stand for some time before being applied to a shoebottom and, on evaporation of the solvent, a crepe, non-skid soleresults.

These grated rubber materials can be used singly or mixed together andthen added to the base composition (milled neoprene, solvent, filler).Of course, when the grated rubber mixture contains some unvulcanizednatural GRS or GN, AC, or S neoprene, it is necessary to apply thecomposition to the sole before these particular rubbers have dissolvedin the solvent. From about 50 to about 200 parts by weight of gratedrubber to 100 parts by weight of the dry, milled neoprene are used inthe composition. It is preferred, however, to use from about 50 to about100 parts of grated rubber per 100 parts of the dry, milled neoprene. Ifless than 50 parts of the grated rubber are used, the'composition ondrying has no crepe appearance. On the other hand, over 200 parts of thegrated rubber results in a crepe sole composition that lacks therequisite strength.

After the rubber has been grated, it is thoroughly mixed with, ordispersed in, the neoprene base composition. The mixing time for smallbatches, i. e., enough for a pair of shoes, will take from about 2 toabout 5 minutes. Larger batches will take obviously longer times. Themixing equipment is not critical and any suitable type can be utilized.

The thoroughly mixed crepe shoe sole composition can now be readilyapplied by unskilled persons at home to a shoe bottom which has beenroughened, cleaned, and dried. It is preferred to first rub some of thecrepe composition over the entire surface of the prepared shoe bottom.This thin layer does not have to thoroughly dry. A spatula can be usedto apply a thick coating of the composition to the shoe bottom. In placeof a spatula it is obvious that a knife or other simple tool can beemployed. As soon as a skim coat has formed on the surface of the thickcoating, the coating can be shaped to conform to the configuration ofthe shoe bottom by'means of the spatula dipped in water to prevent theadherence of the crepe composition to it. Alternatively, the coating canbe shaped before the skim coat forms by means of the spatula. Afterapplying the composition sole, the shoes are placed with their soles upin order to dry. Thick coats or soles take about 48 hours to dry. Thincoats take about 24 hours. The time for drying will, of course, dependon the thickness of the composition. Since the thick coating applied allat once will contract on thorough drying and also tend to be lesspleasing to the appearance and have less wearability, it is desirable toapply the shoe sole composition in successive layers which are moldedwith the spatula and allowed to partially dry or to form a skim coatuntil the desired thickness has been achieved. For example, a coating ofthe composition A thick will on drying be about 1 1; to thick. Byapplying successive coats an unskilled person can obtain a waterproofsole of the desired shape and dimensions which is similar in appearanceto machine-made crepe soles.

The base composition containing a volatile solvent and a filler hasexcellent keeping qualities if suitably packaged so that the solventwill not readily evaporate. The material does not need to be usedimmediately after compounding as no polymerization or other adversereactions set in. Packaged in commercially available per 100 parts ofdry milled neoprene will serve to prevent this discoloration. Magnesiumoxide in an amount up to four parts per parts of dry neoprene will alsoserve to improve the stability of the composition. The grated rubbermaterial can likewise be stored for extended periods of time withoutdeterioration if suitably packaged.

The following example will serve to illustrate the invention with moreparticularity to those skilled in the art:

25 parts by weight (about 1.5 pounds) of neoprene were milled for 20minutes on a 6 x 12 inch 2-roll rubber mill having a clearance betweenrollers of approximately 0.030. The speed of the front roll was 18 R. P.M. while the speed of the rear roll was 26 R. P. M. The gear ratio wasthus about 1.4. The rolls were cooled by circulating water through them.After milling, the neoprene was removed from the mill and dissolved in75 parts by weight of a hydrocarbon solvent composed of 40 per centtoluene and 60 per cent gasoline. To this solution was then added 10parts by weight of leather fibers and 1.25 parts by weight ofcoumarone-indene resin, both based on the dry weight of the neoprene,which was then thoroughly stirred. To the resulting base compositionthere was then added 25 parts of grated rubber from vulcanized naturalrubber tubes. The mixture was thoroughly stirred for about 5 minutesuntil the natural rubber particleswere completely dispersed throughoutthe base composition or solution. The resulting, semi-solid, or plasticmass was immediately applied by means of a spatula to a clean, dry,roughened oak tan shoe bottom to form a sole about thick without the useof any heat, pressure, adhesives, etc. After an air drying period ofabout 48 hours, the non-skid crepe composition shoe sole was tested andits adherence and wearability were found to be excellent.

This crepe, non-skid shoe sole composition can be applied to heels aswell as to shoe bottoms. It adheres readily to previous soles of thiscrepe composition. It will adhere also to the soles of shoes where thesole is firmly attached to the shoe bottom and is in good condition,therefore eliminating the need of removing the old shoe sole. It maylikewise be used to cover the sides or uppers of the shoe to render themwaterproof. Likewise, the crepe, non-skid soling composition can be usedto coat other composition soles or rubber soles as found in slippers,boots, rubbers, galoshes, etc. By roughening, cleaning, and drying thebottom of the footwear, the crepe soling composition, when addedthereto, adheres as satisfactorily as when placed on leather bottoms. Inthe case of rubber articles, it is believed that the solvent in thecrepe soling composition partially dissolves the rubber surface layersof the galoshes or rubber forming a strong bond at the interfacebetweenthe old rubber surface and the new composition sole.

In summary, it will be apparent that there has been disclosed herein anovel method of preparing a new and novel non-skid, crepe shoe solecomposition. After the rubber particles and fibers have been dispersedthroughout a neoprene solution, and on evaporation of the solvent beforethe rubber particles have dissolved therein, the rubber particles willretain substantiallly their former appearance and be bonded with thefibers in a continuous phase of milled neoprene resulting in a crepe,non-skid sole. It is thought that by thoroughly mixing the finelydivided rubber particles with the neoprene base composition, each rubberparticle is coated with a solution containing a material having adhesiveproperties. The rubber particles appear to be firmly bonded with thefibrous filler in the continuous phase or matrix of milled neoprene forno cracking, separation, etc., of the coating occurs on drying. This isprobably due to the fact that the outer layers of each rubber particlesoften or gel somewhat, permitting a bond or weld to exist between therubber particles, the filler and the milled neoprene, making the solealso resilient and flexible as Well as adherent. It is also believedthat the increased density of the mass resulting from the intimateassociation of fine particles, i. e., fibrous and non-fibrous fillers,milled neoprene and grated rubber, renders the composition tough andlong wearing. Such porosity as may exist in the dried coating is in theform of microscopic air pockets which are probably unconnected, for thedried coating is actually not only Water resistant but waterproof andwill not take up oil. This invention thus provides a novel, easy andinexpensive process to enable skilled and non-skilled persons to make orrepair shoe soles, utilizing a moldable, self-adherent, non-skid, crepecomposition, eliminating the former steps of sheeting, vulcanizing,curing, cutting or prestamping crepe materials before applying them toshoe bottoms as well as the need for binding materials or operations.

It is to be understood that while the invention has been described withparticular emphasis on the heeling and soling of shoes, it is quiteobvious that the composition and its method of preparation andapplication, as described herein, have a great many other uses. Thisnovel composition will be useful wherever a crepe, non-skid, moldable,and self-adherent coating material is required.

What is claimed is:

1. A crepe, non-skid composition consisting essentially of 100 parts byweight of polymerized chloro-2-butadiene-l,3 having plasticity numbersin millimeters of 302 to 377 and recovery numbers of 38 to 53 at 80 C.and three minutes, a specific gravity of about 1.23 and which gels butdoes not dissolve in hydrocarbon solvents prior to milling which hasbeen milled until it has ASTM plasticity numbers of from 355 to 280 at80 C. and is soluble in hydrocarbon solvents, from 250500 parts byweight of a volatile hydrocarbon solvent for said milled polymerizedchloro-2-butadiene-1,3, from 2 to 20 parts by weight of a tack-improvingorganic resin from the group consisting of wood rosin, hydrogenatedmethyl abietate, polyhydric alcohol ester of hydrogenated rosin, estergum, phenol-formaldehyde resins, resorcinol-formaldehyde resins, andcoumarone-indene resins, from 20 to 125 parts by Weight of a filler ofwhich at least 40 per cent is fibrous and organic and the balancenonfibrous, and from 50 to 200 parts by weight of ground rubber of'aparticle size suflicient to provide a crepe effect on solidifying andnot substantially greater than 8 mesh, and which has not dissolved insaid solvent.

2. A crepe, non-skid composition consisting essentially of 100 parts byweight of polymerized chloro-2-butadiene-1,3 having plasticity numbersin millimeters of 302 to 377 and recovery numbers of 38 to 53 at C. andthree minutes, a specific gravity ofv about 1.23 and which gels but doesnot dissolve in hydrocarbon solvents prior to milling which has beenmilled until it has ASTM plasticity numbers of from 355 to 280 at 80 C.and is soluble in hydrocarbon solvents, from 300-400 parts by weight ofa volatile hydrocarbon solvent for said milled polymerizedchloro-2-butadiene-1,3, from 5 to 10 parts by weight of a tack-improvingorganic resin from the group consisting of wood rosin, hydrogenatedmethyl abietate, polyhydric alcohol ester of hydrogenated rosin, estergum, phenol-formaldehyde resins, resorcinol-formaldehyde resins, andcoumaroneindene resins, from 40 to 80 parts by weight of a filler ofwhich at least 40 per cent is fibrous and organic and the balancenonfibrous, and from 50 to parts by weight of ground rubber of aparticle size suificient to provide a crepe efiect on solidifying andnot substantially greater than 8 mesh, and which has not dissolved insaid solvent.

CECIL F. BACKUS.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,786,907 Geppert Dec. 30, 1930 2,041,223 Bollman May 19, 19362,103,884 Wentworth Dec. 28, 1937 2,300,352 Earle Oct. 27, 19422,332,000 Murray Oct. 19, 1943 2,431,001 Sullivan Nov. 18, 1947 FOREIGNPATENTS Number Country Date 538,992 Germany Nov. 23, 1931 OTHERREFERENCES Scott, Trans. Inst. of Rubber Industry Aug. 1944, pp. 53-58.

Bake, Neoprene Type AC Report No, 48-3 June 1948, pp. 1-7, 10-12, 15.Rubber Chemicals Division, Du Pont, Wilmington, Del.

1. A CREPE, NON-SKID COMPOSITION CONSISTING ESSENTIALLY OF 100 PARTS BYWEIGHT OF POLYMERIZED CHLORO-2-BUTADIENE-1,3 HAVING PLASTICITY NUMBERSIN MILLIMETERS OF 302 TO 377 AND RECOVERY NUMBERS OF 38 TO 53 TO 80* C.AND THREE MINUTES, A SPECIFIC GRAVITY OF ABOUT 1.23 AND WHICH GELS BUTDOES NOT DISSOLVE IN HYDROCARBON SOLVENTS PIROR TO MILLING WHICH HASBEEN MILLED UNTIL IT HAS ASTM PLASTICITY NUMBERS OF FROM 355 TO 280 AT80* C. AND IS SOLUBLE IN HYDROCARBON SOLVENTS, FROM 250-500 PARTS BYWEIGHT OF A VOLATILE HYDROCARBON SOLVENT FOR SAID MILLED POLYMERIZEDCHLORO-2-BUTADIENE-1,3, FROM 2 TO 20 PARTS BY WEIGHT OF A TACK-IMPROVINGORGANIC RESIN FROM THE GROUP CONSISTING OF WOOD ROSIN, HYDROGENATEDMETHYL ABIETATE, POLYHYDRIC ALCOHOL ESTER OF HYDROGENATED ROSIN, ESTERGUM, PHENOL-FORMALDEHYDE RESINS, RESORCINOL-FORMALDEHYDE RESINS, ANDCEUMARONE-INDENE RESINS, FROM 20 TO 125 PARTS BY WEIGHT OF A FILLER OFWHICH AT LEAST 40 PER CENT IS FIBROUS AND ORGANIC AND THE BALANCENONFIBROUS, AND FROM 50 TO 200 PARTS BY WEIGHT OF GROUND RUBBER OF APARTICLE SIZE SUFFICIENT TO PROVIDE A CREPE EFFECT ON SOLIDIFYING ANDNOT SUBSTANTIALLY GREATER THAN 8 MESH, AND WHICH HAS NOT DISSOLVED INSAID SOLVENT.